package com.summer.dao;

import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;

/**
 * 作者:夏天
 * qq:1205232048
 */
//操作数据库的公共类
public class BaseDao {
    private static String driver;
    private static String url;
    private static String username;
    private static String password;

    //静态代码块 类加载就执行 只执行一次
    static {
        Properties properties = new Properties();
        InputStream resourceAsStream = BaseDao.class.getClassLoader().getResourceAsStream("db.properties");
        try {
            properties.load(resourceAsStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
        driver = properties.getProperty("driver");
        url = properties.getProperty("url");
        username = properties.getProperty("username");
        password = properties.getProperty("password");
    }

    //获取数据库连接
    public static Connection getConnection(){
        Connection connection = null;
        try {
            Class.forName(driver);
            connection = DriverManager.getConnection(url,username,password);
        } catch (SQLException e) {
            e.printStackTrace();
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        return connection;
    }

    //查询公共类
    public static ResultSet execute(Connection connection,PreparedStatement preparedStatement,ResultSet resultSet,String sql,Object[] params) throws SQLException {

        preparedStatement = connection.prepareStatement(sql);
        for (int i = 0; i < params.length; i++) {
            preparedStatement.setObject(i+1, params[i]);
        }
        resultSet = preparedStatement.executeQuery();

        return resultSet;
    }

    //更新公共类
    public static int execute(Connection connection,PreparedStatement preparedStatement,String sql,Object[] params) throws SQLException {
        preparedStatement = connection.prepareStatement(sql);
        for (int i = 0; i < params.length; i++) {
            preparedStatement.setObject(i+1, params[i]);
        }
        int updateRows = preparedStatement.executeUpdate();
        return updateRows;
    }

    //关闭流
    public static boolean closeResource(Connection connection,PreparedStatement preparedStatement,ResultSet resultSet){
        boolean closeResourceFlag = true;
        if(resultSet != null){
            try {
                resultSet.close();
                resultSet = null;//GC会回收null对象
            } catch (SQLException e) {
                e.printStackTrace();
                closeResourceFlag = false;
            }
        }

        if(preparedStatement != null){
            try {
                preparedStatement.close();
                preparedStatement = null;
            } catch (SQLException throwables) {
                throwables.printStackTrace();
                closeResourceFlag = false;
            }
        }

        if(connection != null){
            try {
                connection.close();
                connection = null;
            } catch (SQLException throwables) {
                throwables.printStackTrace();
                closeResourceFlag = false;
            }
        }
        return closeResourceFlag;
    }
}
